/**
 * @file
 * AutoIP Automatic LinkLocal IP Configuration
 *
 * This is a AutoIP implementation for the lwIP TCP/IP stack. It aims to conform
 * with RFC 3927. It uses IPv4 address conflict detection to evaluate the chosen
 * address. The ACD module aims to be conform to RFC 5227.
 * RFC 5227 is extracted out of RFC 3927 so the acd module fits nicely in
 * autoip.
 *
 * @defgroup autoip AUTOIP
 * @ingroup ip4
 * AUTOIP related functions
 * USAGE:
 *
 * define @ref LWIP_AUTOIP 1 in your lwipopts.h
 *
 * Without DHCP:
 * - Call autoip_start() after netif_add().
 *
 * With DHCP:
 * - define @ref LWIP_DHCP_AUTOIP_COOP 1 in your lwipopts.h.
 * - Configure your DHCP Client.
 *
 * @see netifapi_autoip
 */

/*
 *
 * Copyright (c) 2007 Dominik Spies <kontakt@dspies.de>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Author: Dominik Spies <kontakt@dspies.de>
 */

#include "lwip/opt.h"

#if LWIP_IPV4 &&                                                               \
    LWIP_AUTOIP /* don't build if not configured for use in lwipopts.h */

#include "lwip/mem.h"
/* #include "lwip/udp.h" */
#include "lwip/ip_addr.h"
#include "lwip/netif.h"
#include "lwip/autoip.h"
#include "lwip/acd.h"
#include "lwip/etharp.h"
#include "lwip/prot/autoip.h"

#include <string.h>

/**
 * Macro that generates the initial IP address to be tried by AUTOIP.
 * If you want to override this, define it to something else in lwipopts.h.
 */
#ifndef LWIP_AUTOIP_CREATE_SEED_ADDR
#define LWIP_AUTOIP_CREATE_SEED_ADDR(netif)                                    \
    lwip_htonl(AUTOIP_RANGE_START +                                            \
               ((u32_t)(((u8_t)(netif->hwaddr[4])) |                           \
                        ((u32_t)((u8_t)(netif->hwaddr[5]))) << 8)))
#endif /* LWIP_AUTOIP_CREATE_SEED_ADDR */

/* Function definitions */
static void autoip_restart(struct netif *netif);
static void autoip_create_addr(struct netif *netif, ip4_addr_t *ipaddr);
static err_t autoip_bind(struct netif *netif);
static void autoip_conflict_callback(struct netif *netif,
                                     acd_callback_enum_t state);

/**
 * @ingroup autoip
 * Set a statically allocated struct autoip to work with.
 * Using this prevents autoip_start to allocate it using mem_malloc.
 *
 * @param netif the netif for which to set the struct autoip
 * @param autoip (uninitialised) autoip struct allocated by the application
 */
void autoip_set_struct(struct netif *netif, struct autoip *autoip) {
    LWIP_ASSERT_CORE_LOCKED();
    LWIP_ASSERT("netif != NULL", netif != NULL);
    LWIP_ASSERT("autoip != NULL", autoip != NULL);
    LWIP_ASSERT("netif already has a struct autoip set",
                netif_autoip_data(netif) == NULL);

    /* clear data structure */
    memset(autoip, 0, sizeof(struct autoip));
    /* autoip->state = AUTOIP_STATE_OFF; */
    netif_set_client_data(netif, LWIP_NETIF_CLIENT_DATA_INDEX_AUTOIP, autoip);
}

/**
 * @ingroup autoip
 * Remove a struct autoip previously set to the netif using autoip_set_struct()
 *
 * @param netif the netif for which to set the struct autoip
 */
void autoip_remove_struct(struct netif *netif) {
    LWIP_ASSERT_CORE_LOCKED();
    LWIP_ASSERT("netif != NULL", netif != NULL);
    LWIP_ASSERT("netif has no struct autoip set",
                netif_autoip_data(netif) != NULL);

    netif_set_client_data(netif, LWIP_NETIF_CLIENT_DATA_INDEX_AUTOIP, NULL);
}

/** Restart AutoIP client and check the next address (conflict detected)
 *
 * @param netif The netif under AutoIP control
 */
static void autoip_restart(struct netif *netif) {
    struct autoip *autoip = netif_autoip_data(netif);
    autoip->tried_llipaddr++;
    autoip_start(netif);
}

/**
 * Create an IP-Address out of range 169.254.1.0 to 169.254.254.255
 *
 * @param netif network interface on which create the IP-Address
 * @param ipaddr ip address to initialize
 */
static void autoip_create_addr(struct netif *netif, ip4_addr_t *ipaddr) {
    struct autoip *autoip = netif_autoip_data(netif);

    /* Here we create an IP-Address out of range 169.254.1.0 to 169.254.254.255
     * compliant to RFC 3927 Section 2.1
     * We have 254 * 256 possibilities */

    u32_t addr = lwip_ntohl(LWIP_AUTOIP_CREATE_SEED_ADDR(netif));
    addr += autoip->tried_llipaddr;
    addr = AUTOIP_NET | (addr & 0xffff);
    /* Now, 169.254.0.0 <= addr <= 169.254.255.255 */

    if (addr < AUTOIP_RANGE_START) {
        addr += AUTOIP_RANGE_END - AUTOIP_RANGE_START + 1;
    }
    if (addr > AUTOIP_RANGE_END) {
        addr -= AUTOIP_RANGE_END - AUTOIP_RANGE_START + 1;
    }
    LWIP_ASSERT("AUTOIP address not in range",
                (addr >= AUTOIP_RANGE_START) && (addr <= AUTOIP_RANGE_END));
    ip4_addr_set_u32(ipaddr, lwip_htonl(addr));

    LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
                ("autoip_create_addr(): tried_llipaddr=%" U16_F ", %" U16_F
                 ".%" U16_F ".%" U16_F ".%" U16_F "\n",
                 (u16_t)(autoip->tried_llipaddr), ip4_addr1_16(ipaddr),
                 ip4_addr2_16(ipaddr), ip4_addr3_16(ipaddr),
                 ip4_addr4_16(ipaddr)));
}

/**
 * Configure interface for use with current LL IP-Address
 *
 * @param netif network interface to configure with current LL IP-Address
 */
static err_t autoip_bind(struct netif *netif) {
    struct autoip *autoip = netif_autoip_data(netif);
    ip4_addr_t sn_mask, gw_addr;

    autoip->state = AUTOIP_STATE_BOUND;

    LWIP_DEBUGF(
        AUTOIP_DEBUG | LWIP_DBG_TRACE,
        ("autoip_bind(netif=%p) %c%c%" U16_F " %" U16_F ".%" U16_F ".%" U16_F
         ".%" U16_F "\n",
         (void *)netif, netif->name[0], netif->name[1], (u16_t)netif->num,
         ip4_addr1_16(&autoip->llipaddr), ip4_addr2_16(&autoip->llipaddr),
         ip4_addr3_16(&autoip->llipaddr), ip4_addr4_16(&autoip->llipaddr)));

    IP4_ADDR(&sn_mask, 255, 255, 0, 0);
    IP4_ADDR(&gw_addr, 0, 0, 0, 0);

    netif_set_addr(netif, &autoip->llipaddr, &sn_mask, &gw_addr);
    /* interface is used by routing now that an address is set */

    return ERR_OK;
}

/**
 * Handle conflict information from ACD module
 *
 * @param netif   network interface to handle conflict information on
 * @param state   acd_callback_enum_t
 */
static void autoip_conflict_callback(struct netif *netif,
                                     acd_callback_enum_t state) {
    struct autoip *autoip = netif_autoip_data(netif);

    switch (state) {
    case ACD_IP_OK:
        autoip_bind(netif);
        break;
    case ACD_RESTART_CLIENT:
        autoip_restart(netif);
        break;
    case ACD_DECLINE:
        /* "delete" conflicting address so a new one will be selected in
         * autoip_start() */
        ip4_addr_set_any(&autoip->llipaddr);
        autoip_stop(netif);
        break;
    default:
        break;
    }
}

/**
 * @ingroup autoip
 * Start AutoIP client
 *
 * @param netif network interface on which start the AutoIP client
 */
err_t autoip_start(struct netif *netif) {
    struct autoip *autoip = netif_autoip_data(netif);
    err_t result = ERR_OK;

    LWIP_ASSERT_CORE_LOCKED();
    LWIP_ERROR("netif is not up, old style port?", netif_is_up(netif),
               return ERR_ARG;);

    if (autoip == NULL) {
        /* no AutoIP client attached yet? */
        LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,
                    ("autoip_start(): starting new AUTOIP client\n"));
        autoip = (struct autoip *)mem_calloc(1, sizeof(struct autoip));
        if (autoip == NULL) {
            LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,
                        ("autoip_start(): could not allocate autoip\n"));
            return ERR_MEM;
        }
        /* store this AutoIP client in the netif */
        netif_set_client_data(netif, LWIP_NETIF_CLIENT_DATA_INDEX_AUTOIP,
                              autoip);
        LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,
                    ("autoip_start(): allocated autoip\n"));
    }

    if (autoip->state == AUTOIP_STATE_OFF) {
        LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
                    ("autoip_start(netif=%p) %c%c%" U16_F "\n", (void *)netif,
                     netif->name[0], netif->name[1], (u16_t)netif->num));

        /* add acd struct to list*/
        acd_add(netif, &autoip->acd, autoip_conflict_callback);

        /* In accordance to RFC3927 section 2.1:
         * Keep using the same link local address as much as possible.
         * Only when there is none or when there was a conflict, select a new
         * one.
         */
        if (!ip4_addr_islinklocal(&autoip->llipaddr)) {
            autoip_create_addr(netif, &(autoip->llipaddr));
        }
        autoip->state = AUTOIP_STATE_CHECKING;
        acd_start(netif, &autoip->acd, autoip->llipaddr);
    } else {
        LWIP_DEBUGF(
            AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
            ("autoip_start(): already started on netif=%p %c%c%" U16_F "\n",
             (void *)netif, netif->name[0], netif->name[1], (u16_t)netif->num));
    }

    return result;
}

/**
 * Handle a possible change in the network configuration: link up
 *
 * If there is an AutoIP address configured and AutoIP is not in cooperation
 * with DHCP, start probing for previous address.
 */
void autoip_network_changed_link_up(struct netif *netif) {
    struct autoip *autoip = netif_autoip_data(netif);

    if (autoip && (autoip->state != AUTOIP_STATE_OFF) &&
        !LWIP_DHCP_AUTOIP_COOP) {
        LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,
                    ("autoip_network_changed_link_up(): start acd\n"));
        autoip->state = AUTOIP_STATE_CHECKING;
        /* Start acd check again for the last used address */
        acd_start(netif, &autoip->acd, autoip->llipaddr);
    }
}

/**
 * Handle a possible change in the network configuration: link down
 *
 * If there is an AutoIP address configured and AutoIP is in cooperation
 * with DHCP, then stop the autoip module. When the link goes up, we do not want
 * the autoip module to start again. DHCP will initiate autoip when needed.
 */
void autoip_network_changed_link_down(struct netif *netif) {
    struct autoip *autoip = netif_autoip_data(netif);

    if (autoip && (autoip->state != AUTOIP_STATE_OFF) &&
        LWIP_DHCP_AUTOIP_COOP) {
        LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,
                    ("autoip_network_changed_link_down(): stop autoip\n"));
        autoip_stop(netif);
    }
}

/**
 * @ingroup autoip
 * Stop AutoIP client
 *
 * @param netif network interface on which stop the AutoIP client
 */
err_t autoip_stop(struct netif *netif) {
    struct autoip *autoip = netif_autoip_data(netif);

    LWIP_ASSERT_CORE_LOCKED();
    if (autoip != NULL) {
        autoip->state = AUTOIP_STATE_OFF;
        if (ip4_addr_islinklocal(netif_ip4_addr(netif))) {
            netif_set_addr(netif, IP4_ADDR_ANY4, IP4_ADDR_ANY4, IP4_ADDR_ANY4);
        }
        LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE, ("autoip_stop()\n"));
    }
    return ERR_OK;
}

/** check if AutoIP supplied netif->ip_addr
 *
 * @param netif the netif to check
 * @return 1 if AutoIP supplied netif->ip_addr (state BOUND),
 *         0 otherwise
 */
u8_t autoip_supplied_address(struct netif *netif) {
    struct autoip *autoip = netif_autoip_data(netif);
    return (autoip != NULL) &&
           (ip4_addr_eq(netif_ip4_addr(netif), &(autoip->llipaddr))) &&
           (autoip->state == AUTOIP_STATE_BOUND);
}

u8_t autoip_accept_packet(struct netif *netif, const ip4_addr_t *addr) {
    struct autoip *autoip = netif_autoip_data(netif);
    return (autoip != NULL) && (ip4_addr_eq(addr, &(autoip->llipaddr))) &&
           (autoip->state == AUTOIP_STATE_BOUND);
}

#endif /* LWIP_IPV4 && LWIP_AUTOIP */
